Diabetic Ketoacidosis (DKA)

 

• Background

  An acute, severe manifestation of insulin deficiency, usually due to type 1 diabetes.

  Pathophysiology

  ↓↓Insulin leads to:

  • ↑Glucose
  • ↑Ketones
  • ↓pH and ↓HCO3-
  • Dehydration from polyuria and vomiting → renal impairment.

  Causes:

  • Can occur in a patient who is not known to be diabetic i.e. the presenting complaint.
  • Poor diabetic control.
  • Illness: infection, surgery, MI.
  • Insulin pump failure.

  Severity classification

  Classification by pH:

  • <7.3: mild.
  • <7.2: moderate.
  • <7.1: severe.

• Signs and symptoms

  Symptoms:

  • Nausea and vomiting. Due to gastroparesis and attempt to remove H+.
  • Abdo pain.
  • Polydipsia+uria
  • Lethargy
  • ↓Level of consciousness.

  Signs:

  • ↓BP
  • ↑HR
  • Dehydration
  • Kussmaul's (deep) breathing to compensate for acidosis.
  • Ketone smell on breath.
  • Signs of cause e.g. infection.

• Diagnosis and investigations

  Criteria (all 3 required):

  1. Capillary glucose >11 mmol/L or known diabetes.
  2. Capillary/serum ketones ≥3 or urine 2+.
  3. Venous pH <7.3 or HCO3- <15.

  Other investigations:

  • ↑Urea + Creatinine
  • Altered electrolytes: mostly ↓ as lost in urine. Exception is ↑K+ in ⅓, as though there is a low body total, it is ↑ in ECF due to ↓insulin, ↑osmolality, and acidaemia. Will drop after patient is given insulin.
  • ↑Anion gap
  • ↑Osmolality
  • ↑WCC, even if no infection.
  • ↑Amylase

• Management

  1. Normal saline through large bore cannula:

  • If SBP <90, give 500ml/15mins, and repeat if required.
  • If/when SBP >90, give 1L/1hr, then 1L/2hr x 2 (i.e. 2L/4hr), then 1L in 4h x 2, then 1L in 6h.
  • Summary: '½ in ¼ if <90, then 1L in 122446'.
  • In kids, calculate appropriate fluids for weight. Give the dehydration correction amount over 48h, and if bolus given for dehydration (though not if given for shock), deduct it from the correction volume.

  2. K+ IV if <5.5 mmol/L:

  • Don't include in first bag of fluids. Dehydration may cause AKI so that should be treated first.
  • If K+ <3.5, stop insulin until K+ normalised.

  3. Insulin IV: 0.1 unit/kg/hr. 50 units short/rapid acting insulin in bag with normal saline made up to 50 ml. If glucose remains high (>7) after 2 hours, increase dose.

  4. Assess patient and carry out investigations, including a septic screen (at least FBC and CXR). Consider HDU transfer if severe:

  • Ketones >6
  • K+ <3.5
  • GCS <12
  • Acid-base: HCO3-<5, pH <7.1, anion gap >16.
  • Vitals: O2 <92%, SBP <90, HR <60 or >100

  5. Monitor:

  • Continuous O2 sats and ECG.
  • Every hour: capillary glucose should drop 3/hr, ketones should drop 0.5/hr, venous blood gas (HCO3- should rise 3/hr).
  • U&E should be done initially, then 2-hourly, then 4-hourly.

  6. 10% glucose, 125 ml/hr, when glucose <14 and then continue until patient is eating.

  7. Resolution should be seen within 24h, when ketones <0.3 and venous pH >7.3:

  • Once eating and drinking, switch to subcutaneous insulin, overlapping for first 30 mins with IV. Give short acting insulin with meals.
  • If new patient needing to start insulin, give 0.5 unit/kg/day, 50% as basal in evening.
  • If known MDI patient, should have continued basal insulin as usual throughout DKA, but if on twice daily regimen just restart at next meal once resolved.
  • Ensure they are seen by diabetes team within 24h.
  • Consider LMWH.

• Complications

  DKA itself:

  • VTE and PE.

  Iatrogenic:

  • Cerebral oedema, mainly in children. If signs/symptoms develop – headache, altered mental status, pupillary/oculomotor abnormalities, unexpected ↑BP/↓HR, apnoea – treat with mannitol or hypertonic saline.
  • Hypokalaemia
  • Hypoglycaemia